Guo S-X, Li B-Y, Zhang Y, Zhou L-J, Liu L, Widmalm S-E, Wang M-Q
State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi International Joint Research Center for Oral Diseases, Department of Oral Anatomy and Physiology and TMD, School of Stomatology, The Fourth Military Medical University, Xi 'an, China.
Specialist of Stomatognathic Physiology, Division of Prosthodontics, Department of Biological and Materials Sciences, University of Michigan, Ann Arbor, MI, USA.
J Oral Rehabil. 2017 Aug;44(8):594-601. doi: 10.1111/joor.12527. Epub 2017 Jun 22.
Mandibular functions are associated with electromyographic activity of the jaw muscles and also the sternocleidomastoid muscle (SCM). The precise spatiotemporal relation of SCM and masticatory muscles activities during chewing is worthy of investigation. To analyse the sequential recruitment of SCM and masseter activities during chewing as indicated by the spatiotemporal locations of their activity peaks. Jaw movements and bilateral surface electromyographic activity of SCM and masseter were recorded during gum chewing in 20 healthy subjects. The timing order was decided by comparing the length of time from the time when the opening started to the time when the surface electromyographic activity reached its peak value. Spatial order was analysed by locating the peak electromyographic activity onto a standard chewing cycle which was created based on 15 unilateral chewing cycles. Paired t-test, one-way ANOVA and Student-Newman-Keuls post-test were used for comparisons. Although the Time to Peak for the balancing side SCM appeared shorter than for the other three tested muscles, most often it did not reach a level of significance. However, the location of the balancing side SCM's peak activity was further from the terminal chewing position (TCP) than the working side SCM and bilateral masseters (P < 0·05). The balancing side SCM activity reached its peak significantly further away from TCP than the other three tested muscles during chewing. Further studies with spatiotemporal variables included should be helpful to understand the roles of the head, neck and jaw muscles in orofacial and cervical dysfunctional problems.
下颌功能与颌骨肌肉以及胸锁乳突肌（SCM）的肌电活动相关。咀嚼过程中SCM与咀嚼肌活动的确切时空关系值得研究。为了根据其活动峰值的时空位置分析咀嚼过程中SCM和咬肌活动的顺序性募集情况。在20名健康受试者咀嚼口香糖期间记录下颌运动以及SCM和咬肌的双侧表面肌电活动。通过比较从开口开始到表面肌电活动达到峰值的时间长度来确定时间顺序。通过将肌电活动峰值定位到基于15个单侧咀嚼周期创建的标准咀嚼周期上来分析空间顺序。采用配对t检验、单因素方差分析和Student-Newman-Keuls事后检验进行比较。尽管平衡侧SCM的峰值时间似乎比其他三块受试肌肉短，但大多数情况下未达到显著水平。然而，平衡侧SCM峰值活动的位置比工作侧SCM和双侧咬肌更远离终末咀嚼位置（TCP）（P < 0·05）。咀嚼过程中，平衡侧SCM活动达到峰值时比其他三块受试肌肉更远离TCP。纳入时空变量的进一步研究将有助于理解头、颈和颌骨肌肉在口面部和颈部功能障碍问题中的作用。
